A numerical analysis of ice fog produced by automobiles

• Main Author: Nelson, William George
• Other Authors: Elliott, William P., Boubel, Richard W., Wicks, Charles E., Lowry, William P., Mingle, John G., Hewson, E. Wendell, Mechanical and Nuclear Engineering, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Ice fog; Arctic; Fairbanks; Alaska
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/sb397c62h

A model of an exhaust plume was developed and programmed on a digital computer. The purpose of the model was to predict the concentration and size distribution of ice particles produced from automobile exhaust during arctic conditions. The model accounted for the nucleation, growth, and freezing of the condensed water droplets within the exhaust plume. Modes of nucleation included 1) self nucleation, 2) nucleation by soluble particles, and 3) nucleation by insoluble particles. Conditions defining the base case typified a late model automobile, burning leaded gasoline, which was moving slowly or idling during an ice fog episode in an arctic city. Computed ice particle size distributions and ice particle concentrations agreed with measurements obtained by various researchers during ice fog episodes in the urban areas of Fairbanks, Alaska. Other cases were computed where one or more of the parameters effecting the exhaust plume were varied from their base case values. The results of these computations were then compared with the results from the base case. From these comparisons, conclusions were reached as to how one might vary the parameters effecting the exhaust plume in order to reduce the number and/or increase the size of the ice particles produced. The directions in which to vary the parameters from their base case values, in order to reduce the number and/or increase the size of the ice particles, are noted below. I) Increase the exhaust exit temperature 2) Increase the ambient air temperature 3) Decrease the water vapor content of the exhaust gas 4) Decrease the exit velocity of the exhaust gas 5) Increase the diameter of the exhaust pipe outlet 6) Decrease the concentration of soluble and insoluble particles in the exhaust gas. It was noted that, due to its generality, the model which was developed in this thesis may be used to predict the droplet and/or particle size distribution and concentration in a wide variety of plumes. It was also determined that the condensing vapor in the plume of concern need ...